The invention relates generally to processes of making memory devices including ferrite cores, for the memories of electronic computers, for logic automatic apparatus, for control and communication circuits, monitoring systems and more particularly, it relates to methods of production of ferrite matrices and core memories and to apparatus for performing such methods.
The invention can be employed for the production of ferrite matrices with any desired disposition of the cores at the intersections of the wires in a matrix, as well as for the production of ferrite core memories in the form of carpets, plaits, frameless storage devices of practically any capacity from cores of any size, super-mini cores included.
There are known various methods of making ferrite matrices. One of them comprises the steps of first putting the ferrite cores about the wires extending along one of the coordinates in stacks, then mounting these wires parallel to one another in an array onto a framework, the number of the wires and the number of the cores about each wire corresponding, respectively, to the number of the columns and lines in the matrix to be made.
Then one core is separated from each stack, and the cores are indexed in a desired direction, i.e. each core is positioned at 45 angular degrees with respect to the wire, in either direction, in accordance with the predetermined threading pattern. Thus indexed, the cores are arranged in a row, and a needle is threaded therethrough in the direction of the second coordinate, the needle dragging thereafter a mounting wire, in which way a line of the ferrite matrix is made.
The threading of the cores is continued in the same manner, line by line, and, after the coordinate grid has been completed, the readout-inhibition windings are threaded through.
This method is practiced nowadays as a widely popular manual technique of making ferrite matrices.
The disadvantages of this known method are the difficulty of threading through a line with a needle, on account of the eyelet in each core being diminished by the turned position of the core; the difficulty of butt-soldering the wire to the needle and of subsequent finishing of the soldered joint; the eventuality of harming the cores and the insulation of the mounting wire with the steel needle, particularly, by the pointed end thereof and by the soldered joint; the complications encountered at attempts to mechanize this manual process embracing separation and indexing of the cores, arranging them in the threading zone; and, finally, the fact that it is virtual impossibility of introducing mechanization in this manual process in the case of super-mini cores.
Based on the above-described known method, as applied in the case of relatively large cores having an external diameter above 1 mm, there has been developed an apparatus introducing mechanization into the process of threading ferrite matrices. This known apparatus comprises a framework on which an array of wires having the cores put thereabout is mounted. Extending transversely of the wires is a core separating member in the form of a plurality of contoured combs, of which one retains the stacks of the cores, while the other one, spaced from the first one by a spacer corresponding to the height of the cores, separates by its sharp edge one core from the stack on each wire, whereafter the first comb is driven clear of the separated cores, and they slide down the respective wires. Mounted parallel to the separating member is an indexing member in the form of contoured toothed strips turning the cores in desired directions and fixing them in the turned positions. The contoured strips have a notch at their division zone, which notch acts as the guiding channel for the needle with the threading wire, in the area of the eyelets in the cores.
The above-described apparatus is of a complicated structure and involves the use of numerous precision-manufactured parts.
At present, there are employed apparatus for threading ferrite matrices having the cores of an external diameter in excess of 1 mm. The attempts to create a similar apparatus which would handle cores with the external diameter equal to 0.8 mm have so far proved futile. It should be remembered that the present-day technology involves threading of cores with the external diameter as small as 0.3 mm to 0.6 mm, and even 0.2 mm in certain cases.
It is obvious that the core threading operation, which so far has been a manual one, is bound to become completely automated, if it is to be employed with cores of extremely small diameters. The operation becomes too complicated for the skill of a man, whereas the poor productivity of the manual operation, considered in view of the ever growing demand for ferrite memory devices, makes the automation of this process an outright economic necessity.
Among the disadvantages of the above-specified known apparatus for threading comparatively large cores are: insufficient dependability of separation of the cores from the stacks, the necessity of employing needles, with all the complications this necessity involves (e.g. harming of the cores and of the insulation of the wire, the operation of preparing the needle, the eventuality of the wire breaking loose from the needle in the course of a line threading operation, manual guiding of the needle into the guiding channel). The employment of positive physical turning of the cores of small sizes practically always leads to breaking the cores either partly or completely, greatly strains the eyes of the operator, reduces the productivity of labor; in the case of super-mini cores, as small and as light as dust, the apparatus simply cannot be operated.
There is yet another known method and apparatus for threading ferrite matrices, in accordance with which vibration is employed to position the cores in a specially designed mask-holder in the form of a strip with openings made therethrough, the openings having the outline and the size of a core. The openings are situated in the places which the cores are to occupy in the matrix, with the cores turned strictly at 45.degree. with respect to the lines and columns of the matrix, in accordance with a desired pattern. The mask has a substrate with a tacky layer adhered thereto on one side thereof, so that each opening becomes a cell with a tacky bottom to hold a core. The mask is positioned above the cores, with the tacky layer of the mask facing the cores, and the latter, jumping chaotically under the action of vibration, stick in the cells of the mask.
Once positioned in the mask, the cores are threaded through with hollow needles extending in perpendicular directions, and the coordinate wires are passed through these needles. Then the tacky layer and the mask itself are removed. In this way, the problem of introducing automation into some of the processes of making memory matrices has been solved.
This present-day technique, however, is not free from certain disadvantages: the masks and the needles employed are high-precision, complicated and costly articles. The masks, which are made with great difficulty in the case of mini cores, are not completely filled with the cores in the vibratory machine. Placing the cores manually into the unfilled cells of the mask reduces the productivity and results in harming of the mask itself and of the adjacent cores. The hollow needles for cores which are by far not the tiniest ones, e.g. those having diameters equal to 0.3 mm, 0.17 mm, 0.06 mm, are bound to have the external diameter thereof (for threading but two coordinate wires through a core, considering that the core is turned, and the first wire occupies the space in the eyelet) approximating 60 microns, and the internal diameter of the needles should provide for the passage of a wire not thicker that 40 microns, which is extremely difficult to attain; when the wires are of a considerable length, the process cannot be performed altogether.
The operation of removal of the tacky layer and of the mask itself from the threaded matrix also results in harming of the cores, which further reduces the percentage of acceptable product.
The above technique makes it impossible to perform testing of the electric properties of the cores and replacement thereof, should a core prove faulty, directly in the process of threading, until its completion, since making good of a detected fault in no way simplifies, but, most certainly, complicates the operation, as compared with the alternative of repairing a ready matrix.
The above technique introduces mechanization into that part of manual operation which is the most labor-consuming one, even the major one, but merely a fraction of the entire process of making a ferrite matrix. Numerous operations, including re-filling of the masks, inspection of the filled-in masks, assembling them over the full space of a matrix, indexing of the needles for threading, soldering of the inter-matrix connections of the coordinate wires, repairing of the masks, should a core prove faulty, are still performed manually and greatly strain the eyes of the operator.
The technique makes it possible to do without soldering only in the case of matrices of small capacities; it is impractical in case of super-mini cores having an external diameter below 0.4 mm.